This is a great question. The lack of information on this is available on paypal's site is amazing. Here's what I did find:
How This Card Works:
There’s no annual fee for the Paypal Plus Mastercard. You earn one Paypal Plus Reward point for every dollar you spend with your card, anywhere. Points can be redeemed for Paypal vouchers, good for a cash amount off of your Paypal purchases. These vouchers can be used to pay for items with sellers on Ebay and merchants outside Ebay that accept Paypal payments. The vouchers cannot be used for Ebay express purchases, subscriptions, and Ebay seller fees. Be aware that if the amount of the voucher exceeds the amount of the purchase, any unused amount will be forfeited. All vouchers come with an expiration date as well.
Seeing that paypal neglects to provide much information about it I would suggest not using this card at all. Also there are better programs to use such as http://creditshout.com/discover-more-card-review/
I might have done this if they had provided a means of finding out more information at the start but due to the lack of information I decided against it.
